#include <cmath>
#include <cstdio>
#include <vector>
#include <iostream>
#include <algorithm>
using namespace std;


int main() {
    int q;
    cin>>q;
    while(q--){
        int n;
        cin>>n;
        int x[n];
        int y[n];
        for(int i=0;i<n;i++){
            cin>>x[i]>>y[i];
        }
        int count=0;
        for(int i=0;i<n;i++){
            if(x[i]==x[i-1] || y[i]==y[i-1]){
                count++;
            }
        }
        if(count==n-1){
            cout<<"YES"<<endl;
        }
        else{
            cout<<"NO"<<endl;
        }
    }
    return 0;
}